Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751845AbaKGP1B (ORCPT ); Fri, 7 Nov 2014 10:27:01 -0500 Received: from resqmta-ch2-10v.sys.comcast.net ([69.252.207.42]:52953 "EHLO resqmta-ch2-10v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751251AbaKGP1A (ORCPT ); Fri, 7 Nov 2014 10:27:00 -0500 X-Greylist: delayed 491 seconds by postgrey-1.27 at vger.kernel.org; Fri, 07 Nov 2014 10:27:00 EST Date: Fri, 7 Nov 2014 10:18:46 -0500 Message-Id: <201411071518.sA7FIkLu031394@hobgoblin.ariadne.com> From: worley@alum.mit.edu (Dale R. Worley) To: Chris Friesen CC: martin.petersen@oracle.com, axboe@kernel.dk, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, snitzer@redhat.com In-reply-to: <545C5A1B.9020206@windriver.com> (chris.friesen@windriver.com) Subject: Re: absurdly high "optimal_io_size" on Seagate SAS disk References: <545BA625.40308@windriver.com> <545BAD05.3050800@windriver.com> <545BB3AB.8070409@windriver.com> <545BC88A.7060706@windriver.com> <545C5A1B.9020206@windriver.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > From: Chris Friesen > Also, I think it's wrong for filesystems and userspace to use it for > alignment. In E.4 and E.5 in the "sbc3r25.pdf" doc, it looks like they > use the optimal granularity field for alignment, not the optimal > transfer length. Everything you say suggests that "optimal transfer length" means "there is a penalty for doing transfers *larger* than this", but people have been treating it as "there is a penalty for doing transfers *smaller* than this". But the latter is the "optimal transfer length granularity". Dale -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/